Failure Mechanisms

· Protrusions and intrusions on the surface of a copper single crystal fatigued at room temperature for 120,000 cycles are shown for a total plastic strain of 0.002.
· A cross-section of one of the extrusion features showing initiation of a fatigue crack. The crack has a length of about 10 microns.
· Stage-1 cracks of this type propagate along the direction of maximum shear stress due to complex dislocation interactions in the PSB.

From: Suresh, "Fatigue of Materials," Cambridge (1991)